Posts By: jonny

Batch Auto-Levels on Images

photography, shell

I had a thousand image files the kids had photographed when creating a stop motion video. An ‘auto-levels’ on many of the images was required to brighten them up so at the command line I used the following (with ImageMagick already installed of course):

ImageMagick is impressive – getting through each image in under… Read more »

Customise Yakuake Tabs On Start

ubuntu

Yakuake

I’ve been recommending the slide-down terminal Yakuake to people for some time now and I couldn’t live without it myself. Although I use Cinnamon as a desktop I much prefer Yakuake over Guake and can live with the extra RAM usage of the KDE libraries. When logging in I wanted to have tabs created for… Read more »

Bleeding Edge PHP on CentOS 7

php, red hat centos

The PHP packages in the base / epel repositories are very conservative. To opt for something more current the REMI repo can be used. Install the remi-release package (info)  first:

This will create the remi specific repo files in the /etc/yum.repo.d directory, specifically:

To install later PHP versions alongside your current PHP version… Read more »

Discourse CentOS – which: no docker.io in

red hat centos

This must be my second or third attempt at Discourse having given up several times before and I may well find reasons to avoid it again. The Discourse advice of just use Ubuntu or using DigitalOcean doesn’t cut it for me. One of the problems I ran into today (after following these docker/discourse instructions) was… Read more »

Arduino Serial Port Menu Greyed Out

ubuntu

On Linux Mint (Ubuntu) I had installed the Arduino IDE from the repository and that had installed version 1.0.5. Despite setting the permissions on the Arduino USB device, the ‘Serial Port’ option in the IDE menu was greyed out and would not allow for selecting the device – it thus defaulted to using COM1 –… Read more »

Resetting Drained Slurm Node

red hat centos

After barking up the wrong tree for a while I discovered via StackExchange how to reset a Slurm Node reporting as drained. Run the scontrol command then update the node as shown in the following example commands (amend the word jacob here to the name of your node):

 

MySQL GRANT SELECT on a demo database to all users

mysql

MySQL access to all users

I needed to give all students read access to a demo database and did so with: mysql> GRANT SELECT ON gameofthrones.* TO ”@localhost; Query OK, 0 rows affected (0.00 sec) mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.01 sec)    

Kerberos Keytab File Creation on Ubuntu

ubuntu

To create a kerberos keytab file on Ubuntu and with the kerberos packages installed (e.g. sudo apt-get install krb5-user )

After completing those steps there should be a keyfile created in the current directory. That keytab file can be used instead of using a password. For example:

   

Apache: unable to open logs

apache, linux

In the annals of “Everyday is a learning day”. I have an Apache server hosting student websites, and the number of websites grew to over 700 within a day and Apache was complaining with error:

It took a little while to narrow down the problem as I assumed there was a path that did… Read more »

Customise the Unity Launcher from Command Line

ubuntu

I am rolling out some Linux desktops, specifically Ubuntu, and I wanted to customize the icons available in the Unity Launcher. I wanted to remove the LibreOffce Calc and Impress icons and the darned ‘Amazon’ one, so: Create a new gschema override file for our customisations:

Add some content (the com.canonical.Unity.gschema.xml file in the… Read more »